Filtering cell and corresponding filter

Abstract

A filtering cell including a resonant circuit having an inductor and capacitor connected in parallel, the inductor being separated into two identical inductors which are connected in series with a midpoint therebetween. A second capacitor is connected at the midpoint and has a quality factor substantially equal to a quality factor of the first inductor, resulting in attenuation at the resonant frequency. Each of the inductors and capacitors are formed by micro-ribbon technology.

We claim: 
     
       1. A filtering cell to be connected to a load impedance of value R comprising: a resonant circuit having a first inductor and a first capacitor, said first inductor and capacitor being connected in parallel, said first inductor having an inductance L and a resistance r and having a quality factor of value Lw/r at a pulsation w, said first inductor being separated into two identical inductors each having an inductance equal to half the inductance of said first inductor, said two identical inductors being connected in series with a midpoint therebetween,   a second capacitor connected to said midpoint, said second capacitor having a capacitance Cc substantially equal to L/R 2 , and a resistance R c , said second capacitor having a quality factor of value CcRcw at said pulsation w, said quality factor CcRcw being substantially equal to the quality factor Lw/r of said first inductor.   
     
     
       2. A filtering cell according to claim 1, wherein said first inductor consists of two conductive micro-ribbons deposited on one side of an insulating substrate, and said second capacitor consists of a conductive micro-ribbon deposited on said substrate between said two conductive micro-ribbons, with a conductive plane deposited on the other side of the substrate. 
     
     
       3. A filter including a plurality of filtering cells, wherein at least one of those cells conforms to the cell according to any one of claims 1 or 2.